1. Field of the Invention
The present invention generally relates to hair dryers and, more particularly, is concerned with a hair dryer having a control circuit actuated by manipulating a pair of momentary switches to simultaneously and continuously variably regulate operation of a heater element and blower to produce any desired heated air flow output having any desired heat intensity and air flow speed falling within respective continuous ranges of heat intensities and air flow speeds.
2. Description of the Prior Art
A portable hair dryer typically includes a hollow housing with an inlet and an outlet, an electric blower mounted in the housing which serves as a means for inducing the flow of air through the housing from the inlet to the outlet thereof when the hair dryer is in use, and a heater element mounted in the housing which serves as a means for heating the air flow between the inlet and outlet of the housing. Also, many hair dryers provide different heat intensity levels and air flow speeds to accommodate the variety of needs of different users.
Representative examples of hair dryers with variable heat intensities and air flow speed are the ones disclosed in U.S. patents to Walter et al (U.S. Pat. No. 4,260,875), Long et al (U.S. Pat. No. 4,309,595), Tomaro (U.S. Pat. No. 4,327,278), Maese (U.S. Pat. No. 4,794,225), Thaler et al (U.S. Pat. No. 4,711,988), and Lambert (U.S. Pat. No. 5,195,164).
U.S. Pat. No. 4,260,875 to Walter et al and U.S. Pat. No. 4,309,595 to Long et al each discloses a hair dryer having a switch which is moved between high and low positions to control corresponding levels of both blower speed and power to a heater element. U.S. Pat. No. 4,316,077 to Tomaro discloses a hair dryer having a multiple speed control circuit for providing four heat and two speed levels. U.S. Pat. No. 4,794,225 to Maese discloses a hair dryer having a switch to operate the dryer at several different heat and air flow rates.
U.S. Pat. No. 4,711,988 to Thaler et al discloses a hair dryer having a three-position rocker switch, a two-position rocker switch and a three-position trigger switch for controlling operation thereof. The three-position rocker switch provides control of the blower and heater element and has an "off" position for cutting power off to both the blower and heater element, a "low" position for low blower speed and low heater element heat intensity generation, and a "high" position for high blower speed and high heater element heat intensity generation. The two-position rocker switch has a "warm" position for relative low heat intensity generation rate and a "hot" position for relative high heat intensity generation rate. The three-position trigger switch, which provides independent control of the blower and heater element to provide specialized operational modes for use in hair setting, has a "normal" mode position wherein the other two switches control the blower and heater element as described above, a "cool shot" mode position wherein the heater element generates heat intensity at a reduced rate and the blower speed is slowed, and a "hot shot" mode position wherein the heater element generates heat intensity at least at the normal mode rate and the blower speed is decreased with the result that the air flow is heated to higher temperature. The hair dryer also has an electrical circuit which employs the combination of a diac, triac and capacitor in conjunction with the switches to limit the current supplied thereto and thereby to increase the safety of the dryer.
U.S. Pat. No. 5,195,164 to Lambert discloses a hair dryer having a blower trigger and a heat intensity trigger disposed on the front of a handle grip which are pressed for respectively actuating rebound/spring-loaded, graduated intensity switches mounted within the handle grip being respectively capable of controlling the speed of the blower and the intensity of the heater element. The hair dryer also includes a pair of spring-biased locking buttons on the side of the handle grip for interacting with teeth on the sides of the triggers for selectively locking each of the triggers in a selected position between "off" and the maximum position of the incremental switch actuated by the respective trigger.
Like many conventional hair dryers, the ones of the above-cited patents thus employ one or more switches which permit rates of air flow and heat intensity generation to be set at different levels. One disadvantage is that only a few, such as two to four, discrete speed and heat levels are provided. Either a variable heater element or a plurality of separate heater elements are provided to obtain different heat levels. Another disadvantage is that, in order to provide heat intensity and air flow speed control, separate multiple position switches are used requiring effort and skill to correctly manipulate such switches to regulate the temperature and air speeds as desired.
It appears that none of the prior art hair dryers has achieved the degree and ease of control over heat intensity and air flow speed that is desired by many users. Consequently, a need still exists for a hair dryer having heat intensity and air flow speed control which will overcome the drawbacks of the prior art and meet the expectations of users.